Tidal Power Plants for Power Generation

Tide is a periodic rise and fall of the water level of sea. It may be due to action of sun and moon on sea water. Large scale up and down movement of sea water possesses unlimited source of energy. If some division of this vast energy can be transformed into electrical energy it would be a significant source of hydropower.

Tidal Power Plant:

The below figure illustrates the basic principle of working of a tidal power plant.

Three main components of a Tidal power plant are,

• A dam or barrage (low wall) to form a pool or basin

• Sluice ways from basin to sea and vice versa

• Power house (turbines, electrical generator and other accessories)

The dam serves as a barrier between the sea and the basin or between one basin or and the other.

The main feature of the tidal cycle is the difference in water surface elevation at the high tide and the low tide. This differential head is utilised in operating a hydraulic turbine.

In principle, at the time of high tide, water will be at high level and it is let into a basin to be stored at a high level there. Since the basin water level is high and sea water level is low, there is a differential head that can be utilised for running the turbines. Turbines used in a tidal power plant are reversible type so that they can work as pumps also to pump water out from basin to sea during low tide period.

Turbines are coupled to electrical generators as usual which produced electrical power.

Advantages of Tidal Energy

• Inexhaustible source of energy

• Independent of rain uncertainty

• Free from pollution

• Power plant does not require large area of land because it is installed on sea shore

• Can be used as a supplement to conventional system

Disadvantages of Tidal Energy

• Variability in Output

• Low overall efficiency

• Feasible only at certain stage of tidal cycle

• Sea water being corrosive, machinery gets corroded

• Plant construction is difficult and costly